Introduction to MRI scans
The MRI (Magnetic resonance Imaging) was developed
in the 1980’s and has revolutionized treatment
for patients with low back pain. An MRI scan is
generally considered to be the single best imaging
study of the spine
to help plan treatment for back pain.
Physicians usually have a good idea of what they are
looking for on the MRI scan before one is performed.
The scans are most commonly used for pre-surgical planning,
such as for a decompression or a lumbar spinal fusion.
MRI scans are extremely sensitive to picking up information
about the health of the discs, as well as the presence
of any tumors or a lumbar disc herniation (see
figure 1) pinching the nerve roots
and causing back pain.
In addition to pre-surgical planning, MRI scans are
also very useful for the following:
-
To rule out infection or tumor
-
For patients who have had surgery, to differentiate
scar tissue from a recurrent disc herniation.
-
Prior to performing an epidural injection to rule
out the risk of injecting a steroid into a tumor or
infection
An MRI scan is not the best diagnostic study to assess
a fracture. A computerized Tomography (CT scan) is generally
done for patients who have suffered some trauma (such
as a fall) if a fracture is suspected.
The MRI works by rotating a magnet around a patient,
which changes the excitation level of hydrogen atoms
in the body. When the hydrogen atoms revert back to
their normal level of activity, they emit a slight
amount of radiation that is then picked up on a scanner.
The developed MRI scan image shows anatomy by differentiating
between tissues that have a lot of water (such as
fat, cerebrospinal fluid or discs) and tissues that
do not have much water (such as bone, cartilage, and
nerve roots).
If you have low back pain and/or leg pain and are wondering
if you should get an MRI scan to see what is causing
the pain, the following general rules explain when a
scan is useful and when it is not useful:
|
